Transmission mechanism



May 7, 1940.

'G.SAUER 2.199.678

TRANSMISSION MECHANISM Filed June 4, 1938 2 Sheets-Sheet l a? George ,S'au'er, W ATTORNEYS.

INVENTOR:

May 7, 1940.v G SAUER 2.199.678

TRANSMISSION MECHANISM Filed June 4, 1938 2 Sheets-Sheet 2 w s nu 5 5 I; m! g i i\ Q WITNESSES; 9W "WE/goa- )7 w George auer, ,dlumizfl BY W W A TTORNEYS.

Patented May 7, 1940 TRANSMISSION MECHANISM George Sauer, Berwyn, 111., assignor to Union Special Machine Company, Chicago, 111., a corporation of Illinois Application June4, 1938, Serial No. 211,712

10 Claims.

This invention relates to transmission mechanism useful in operatively connecting multiple shafts, as for example in sewing machines wherein the needle and the complemental stitch forming and feeding mechanisms are respectively actuated from separate shafts.

During the operation of a sewing machine, the needle actuating shaft is called upon to bear periodic loads which vary between wide limits depending upon the extent of resistance encountered by the needle in penetrating fabrics of different kinds or thickness; and this is equally true of the shaft from which the feeding mechanism 4 is actuated due to diverse frictional characteristics in the diiferent fabrics which thus variantly resist progression along the Work support of the machine especially since heavy pressure is exerted upon them from above by the presser foot. As a consequence of the unbalanced and periodic loads borne by the two shafts, rapid and uneven wear takes place in the transmission by which said shafts are operatively connected in the sewing machine, with attendant development of looseness and lost motion in the parts and untiming of the needle movements with respect to those of the complemental stitch-forming and feeding mechanism.

The chief aim of my invention is to obviate the above drawbacks which desideratum I realize as 30. hereinafter more fully explained in a transmission mechanism in which a toothed gear is common to gears respectively on the multiple shafts, the shaft gears being each composed of two sections which are relatively shiftable circumferentially, so

35 that they can be adjusted for wear take-up and back lash compensation with respect to the common gear.

Other objects and attendant advantages will appear from the following detailed description 40 of the attached drawings wherein Fig. I is a View partly in elevation and partly in longitudinal section of a sewing machine conveniently embodying the present improvements.

Fig. II shows the machine in plan with portions 45 broken out and in horizontal section along the staggered plane indicated by the arrows II-II in Fig. I.

The sewing machine which I have chosen for convenience of illustrating my invention is of 50 the lockstitch type and generally resembles the sewing machine disclosed in U. S. Patent No. 2,113,572 granted to Norman V. Christensen and Charles F. Rubel on April 12, 1938. As shown, the machine has an upper horizontal shaft 1 II which is journaled in suitable bearings 2, 3 within a hollow overhanging arm 4 supported at one end by a hollow standard 5 from the work plate 6, and a parallel lower shaft 7 which is journaled in spaced bearings 8, 9 and Ill (Fig. II) afforded by a pendant projection ll of said work support. 5 At the right hand end of the machine, the shaft 1 passes through another bearing [2 into an oil sump 13, which, in effect is a downward continuation of the standard 5 and which is closed at the bottom by a removable cover plate M. The 10 needle l5 of the machine is secured in the lower end of a vertical bar l6 guided for endwise reciprocation in the hollow terminal head i! at the free end of the overhanging arm 4. The needle bar 16 is actuated through the medium of a pit- 15 man l8 from a balanced crank 59 at the left hand end of the upper shaft within the hollow of the head l'l. Cooperating with the needle below the work support is a complemental stitch-forming mechanism, including, in the present instance, a rotary hook 20 which is mounted on a short counter shaft 21 journaled in the projection ll beneath the work support 6, and which is actuated through a pair of intermeshing spur gears 22, 23, from the 25 lower shaft 1, said gears being enclosed in an oil housing 25 afforded by a hollow in said projection. The gears 22, 23 are in the ratio of two to one, so that the rotary hook 20 is caused to revolve twice for each reciprocation of the needle l5. The machine also has a presser foot 26 (Fig. I) which is secured to the lower end of a presser bar 21 confined to up and down movement in-the head I1 and thus is yieldingly urged downward toward the throat plate of the machine indicated at 28. The fabric (not shown) which is to be sewed is advanced transversely of thework support 6 beneath the presser foot 26 by a feed dog 29 mounted on a bar 30 whereof the rear end is pivotally connected to a vertical rocker 3!. At its lower end, the rocker 3| is fulcrumed to swing on a rock shaft 32 journaled in pendant lugs 33 and 34 of the work support 6, see Fig. II. The feed dog 29 derives its horizontal to and fro or feed movements from the lower shaft 1 whereon is mounted an eccentric 35 having a telescopic link connection 36 with the rocker 3|. The feed dog 29 also receives its lift movements from the shaft by means, not shown in the drawings, but which may be like the means provided for a like purpose in the Christensen and Rubel patent hereinbefore referred to. The fabric advancing stroke of the feed dog 29 is adjustable by means of a regulating shaft 3'! which extends parallel to the lower shaft '1 beneath the work support 6. At

its outer or left hand end, the regulating shaft 31 carries an arm 38 which is connected by a lazy bar 39 to one component of the telescoping link 36, in the manner similar to that shown in the Christensen and Rubel patent supra.

The transmission mechanism with which the present invention is more especially concerned, comprises a train of gears which is enclosed within the hollows of the standard and of the downward prolongation |3 thereof. In the present instance there are but three gears in the train, to wit, a pinion 4|] which is mounted on the upper or needle driving shaft a pinion 4| which is mounted on the lower'shaft l, and a common intermediate gear 42 which is mounted between adjustable collars 43 on a shaft 44 extending crosswise of the front and rear walls of the standard 5. The gear pinion 40 is composed of two toothed components or sections 40a, 40b which are relatively shiftable circumferentially and fixable in adjusted positions by means of set screws 45, 46 passing through their respective axial bosses or hubs, so that adjustments may be made from time to time with respect to the intermediate gear 42 of the train for the purpose of taking up wear and compensating for backlash. As shown, the teeth of the sections 46a, 40b of the pinion 40 are of different widths which jointly aggregate the tooth width of the intermediate gear 42. The pinion 4| is likewise composed of two components or sections Ala, Mb, whereof the first is wider than the second, and which together aggregate the tooth width of the gear 42, said sections being circumferentially shiftable relatively on the lower shaft l and securable in adjusted positions by set screws 41, 48 passing through their respective axial bosses or hubs. As a consequence, wear and back lash can be compensated for between the pinion 4| and the intermediate gear 42 independently of the adjustment of the pinion 40. It is to be noted that the sections of the pinion 4| are reversely arranged with relation to the corresponding sections of the pinion 40 for a reason presently explained.

In practice, the sectional gears or pinions 40, 4| and the intermediate gear 42 are made from materials which differ in hardness. Preferably, the pinions 4|], 4| are constructed from metal, and the intermediate or idler gear 42 of either a softer metal or of non-metallic material or composition. Preferably also the teeth of the intermediate gear 42 are so proportioned in num her to the teeth of the pinions 40, 4| that the wear occasioned by shock loads is distributed over all the teeth of said gear. In these characteristics, the gears of the present transmission are like those of the Christensen and Rubel patent.

From the foregoing, it will be seen that with my improved transmission mechanism, the coacting parts which depend upon the two shafts and for their actuation can be maintained in exact timed relation irrespective of the direction of rotation of said shafts. By making the component sections of the pinions 4|! and 4| of different widths and arranging them in reversed relation on their respective shafts, wear which the intermediate gear 42 undergoes is more evenly distributed across the width of the latter. If desired, however, the gear components 40, 4| may be made to equal widths.

As herein shown, the machine is arranged for either manual or power operation by means of a combined hand and belt wheel 49 secured to the protruding rear end of the upper shaft How ever, if desired or found convenient, the lower shaft 1 may be employed as the drive shaft instead of the shaft by extending it rearwardly to the exterior of the machine frame to enable application of the belt wheel thereto. The gear train is lubricated by oil carried up by the lower pinion 4| which runsv partly submerged in a supply maintained at the level L in the sump l3.

While I have illustrated and described my invention as embodied in a lockstitch sewing machine, it may be incorporated, in chain stitch sewing machines without sacrifice of any of the advantages hereinbefore pointed out. Moreover, my improved transmission is not to be regarded as restricted to sewing machines, but is employable in other machines where an unbalanced load condition obtains between a plurality of shafts from which different mechanisms are motivated.

Having thus described my invention, I claim:

1. Transmission mechanism useful to operatively connect two shafts which are subject to varying or periodic loads, including a toothed gear, and pinions respectively on said shafts in mesh with the gear, each composed of a pair of similar toothed sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted for wear take-up and for back-lash compensation in respect to the gear, the components of the pinions being reversely arranged respectively with their faces meeting in different planes for distribution of wear on the gear.

2. Transmission mechanism useful to operatively connect two shafts which are subject to varying or periodic loads including a toothed gear, and pinions respectively on said shafts in mesh with the gear, each composed of a pair of similar toothed sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted for wear take-up and for backlash compensation in respect to the gear, the gear and the pinions being of materials differing in hardness, and the components of the pinions being reversely arranged respectively with their faces meeting in different planes for distribution of wear on the gear.

3. Transmission mechanism useful to operatively connect two shafts which are subject to varying or periodic loads, including a toothed gear; and pinions respectively on said shafts in mesh with the gear, each composed of a pair of similar toothed sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted for wear take-up and for back lash compensation in respect to the gear, said gear being of nonmetallic material and the pinions of metal, and the components of the pinions being reversely arranged respectively with their faces meeting in different planes for distribution of wear on the gear.

4. Transmission mechanism useful to operatively connect two shafts which are subject to varying or periodic loads, including a toothed gear, and pinions respectively on said shafts in mesh with the gear each composed of a pair of similar toothed sections of different widths which are relatively shiftable circumferentially so that said pinions can be independently adjusted for;

wear take-up and for back-lash compensation in respect to the gear, the number of teeth on the gear being so proportioned to the number of Y teeth on the pinions that wear of pinions by shock loads is distributed over all the teeth of said gear, and the components of pinions being reversely arranged respectively with their faces meeting in different planes for further distribution of wear on the gear.

5. Transmission mechanism useful to operatively connect two shafts which are subject to varying or periodic loads including a toothed gear, and pinions respectively on said shafts in mesh with the gear, each composed of a pair of similar toothed sections of different Widths which are relatively shiftable circumferentially so that said pinions can be independently adjusted for wear take-up and for back-lash compensation in respect to the gear, the number of teeth on the gear being so proportioned to the number of teeth on the pinions that wear of the pinions by shock loads is distributed over all the teeth of the gear, said gear and pinions being of materials differing in hardness and the components of pinions being reversely arranged respectively with their faces meeting in different planes for further distribution of wear on the gear.

6. In a sewing machine having two separate shafts from which the needle and the feeding means are respectively actuated, transmission mechanism for operatively connecting the two shafts including a toothed gear, and pinions respectively on said shafts in mesh with the gear each composed of a pair of similar sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted with respect to the gear for wear take-up and for back-lash compensation, the components of said pinions being reversely arranged respectively with their faces meeting in different planes for distribution of wear on the gear.

'7. In a sewing machine having two separate shafts from whichthe needle and the feeding means are respectively actuated, transmission mechanism for operatively connecting the two shafts including a toothed gear, and pinions respectively on said shafts in mesh with the gear, each composed of a pair of similar toothed sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted with respect to the gear for wear take-up and for back-lash compensation, said gear and pinions being of materials differing in hardness, and the components of said pinions being reversely arranged respectively with their faces meeting in different planes for further distribution of wear on the gear.

8. In a sewing machine having two separate shafts from which the needle and the feeding means are respectively actuated, transmission mechanism for operatively connecting the two shafts, including a toothed gear; and pinions respectively on said shafts in mesh with the gear, each composed of a pair of similar toothed sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted with respect to the gear for wear take-up and for back lash compensation, said gear being of non-metallic material and the pinions of metal, and the components of the pinions being reversely arranged respectively with their faces meeting in different planes for distribution of wear on the gear.

9. In a sewing machine having two separate shafts from which the needle and the feeding means are respectively actuated, transmission mechanism for operatively connecting the two shafts including a toothed gear, and pinions respectively on said shafts in mesh with the gear,

, each composed of a pair of similar sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted with respect to the gear for wear take-up and for back-lash compensation, said gear having teeth so proportioned as to number with respect to teeth on the pinions, that wear occasioned by shock loads is distributed over all the teeth of the gear, and said pinions having their components reversely arranged respectively with their faces meeting in different planes for further distribution of wear on the gear.

10. In a sewing machine having two separate shafts from which the needle and the feeding means are respectively actuated, transmission mechanism for operatively connecting the two shafts including a toothed gear of non-metallic material, and pinions of metal respectively on said shafts in mesh with the gear, eachcomposed of a pair of similar sections of different widths which are relatively shiftable circumferentially so that the pinions can be independently adjusted with respect to the gear for wear take-up and for back-lash compensation, the number of teeth on the gear being so proportioned to the number of teeth on the pinions that wear caused by shock loads is distributed over all the teeth of said gear, the components of said pinions being reversely arranged respectively with their faces meeting in different planes for distribution of wear on the gear.

GEORGE SAUER. 

